In image collector devices it is oftentimes important to protect the sensor used for collecting images from harmful factors such as dust and light. An example of an image collector device where this problem may arise is a camera. In some cameras, a lens is mounted in a lens holder by engaging an outer thread on the lens with an inner thread on the lens holder. In this mounting operation, the threads may be slightly damaged or worn, such that metal particles are rubbed off the threads. There may also be cuttings left on the threads from the manufacturing of the lens. The metal particles or cuttings may fall on a sensor arranged behind the lens, and may damage the sensor, or at least decrease the image quality. Particularly, during transportation of cameras, any cuttings stuck on the threads may fall off. One way in which this problem may be dealt with is to apply grease on the thread of the lens, such that any cuttings are caught in the grease and do not fall down on the sensor. However, in some situations, this is not a satisfactory solution, since it does not actually prevent the cuttings from entering the sensor space in which the sensor is arranged, but only retains the cuttings on the threads. Further, mounting of image collector devices is in many cases done in a clean room environment, making grease a difficult additive to handle. Hence, a need remains for a solution to this problem.